Hi all, This series fixes function tracing with clang.
Patch 1 adjusts the mcount regex in scripts/recordmcount.pl to handle the presence of PLT relocations, which happen with clang. Without this, the mcount_loc section will not be created properly. Patch 2 adds a workaround for clang less than 13.0.0 in relation to the mcount symbol name, which was "mcount" rather than "_mcount". This was written as a separate patch so that it can be reverted when the minimum clang version is bumped to clang 13.0.0. Patch 3 avoids a build error when -fpatchable-function-entry is not available, which is the case with clang less than 13.0.0. This will make dynamic ftrace unavailable but all of the other function tracing should work due to the prescence of the previous patch. I am hoping this series can go in as fixes for 5.12, due to patch 3, but if not, they can always be backported (patches 1 and 2 are already marked for stable). This series has been build tested with gcc-8 through gcc-10 and clang-11 through clang-13 with defconfig and nommu_virt_defconfig plus CONFIG_FTRACE=y and CONFIG_FUNCTION_TRACER=y then boot tested under QEMU. Cheers, Nathan Nathan Chancellor (3): scripts/recordmcount.pl: Fix RISC-V regex for clang riscv: Workaround mcount name prior to clang-13 riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is available arch/riscv/Kconfig | 2 +- arch/riscv/include/asm/ftrace.h | 14 ++++++++++++-- arch/riscv/kernel/mcount.S | 10 +++++----- scripts/recordmcount.pl | 2 +- 4 files changed, 19 insertions(+), 9 deletions(-) -- 2.31.0